The statements in this section merely provide background information related to the present disclosure and do not constitute prior art.
An ultrasound probe is adapted to transmit an ultrasonic signal for ultrasonic imaging to an object and receive an ultrasonic echo signal reflected from the object.
Sonic probes may be applied to a variety of industrial fields. In particular, sonic probes are useful for medical apparatus such as an ultrasonic diagnostic apparatus which emits an ultrasonic signal from the outside surface of an object toward a desired internal site of the object and then noninvasively acquire tomograms of soft tissues or bloodstream by using a reflected ultrasonic echo signal.
The principle for an ultrasound probe to transmit and receive ultrasound waves is to utilize the characteristics of piezoelectric materials. A piezoelectric material refers to what interconverts between electrical energy and mechanical energy. For example, the piezoelectric material used for ultrasound probes vibrates and at the same time, emits ultrasound waves, when a voltage is applied across electrodes formed in its upper and lower parts, receives ultrasound waves reflected by a scattering/reflecting object within another object or body and converts the received ultrasound wave into an electrical signal.
An ultrasound probe generally uses a piezo-ceramic, piezo-composite, piezo-single crystal or the like as a piezoelectric material.
PZT is a solid solution material of lead zirconate titanate, which is the most widely used thanks to its manufacturability and superior piezoelectric and dielectric properties.
When taking microscopic observation of PZT having a perovskite structure, grain boundaries are present having dipoles therein. Dipoles have polarity, but face randomly different directions. Accordingly, the overall polarity of dipoles is zero, which exhibits no piezoelectricity.
However, piezoelectricity may be generated by a poling process for applying a voltage to a piezoelectric material. When the electrical energy is applied to the piezoelectric material, polarization is established whereby dipoles are polarized and rotated, and are then aligned in one direction. As a result, the piezoelectric material becomes available for operation.
A typical process for manufacturing ultrasound probes uses a piezoelectric material in which dipoles are aligned in one direction. In other words, machining and laminating are performed on the polarized piezoelectric material. However, it is disadvantageous that polarized piezoelectric materials, in particular, single crystalline piezoelectric materials are easily damaged by size-cutting or dicing and have low mechanical workability such as non-uniform dicing.